1. Field of the Invention
The present invention relates to a method and apparatus for capturing a motion of a dynamic object, and more particularly, to a method and apparatus for capturing a motion of dynamic object which restore appearance information of an object making a dynamic motion, and motion information of a main joint by only an image sensor for a visible light range.
2. Description of the Related Art
General techniques for capturing appearance and motion information of an object making a dynamic motion are being performed on human bodies and can be generally classified into two kinds.
First, there is a method for capturing a dynamic motion of an object by scanning static appearance information of the object by using an active sensor for a laser or pattern light, capturing a joint motion by attaching markers to parts of the object having a great dynamic effect and tracking the markers, and manually combining two kinds of information by a designer.
This method is actually used a lot for high-quality special effects in image contents such as films or commercial films; however, there is a drawback in which, in order to combine information obtained by different kinds of sensors, a lot of manual labor of skilled designers and artists and a large amount of model generating time are required.
Scanned static appearance information has a shape different from a mesh structure used for expressing a dynamic motion as in FIG. 3, but it is not appropriate for generating a smooth motion because of excessive capacity and a random structure. Therefore, it is inevitable to go through a process of regenerating a mesh structure to easily construct animation on the basis of appearance information scanned by manual labor. In this process, in order to preserve behavioral characteristics of an actual dynamic object, a lot of tuning work is required. Further, a rigging process which is an animation connection process between a skeletal structure of a dynamic object and individual vertexes constituting a mesh structure assigns the captured motion information to a joint of the skeletal structure and is tuned by repeated manual labor until the appearance information modified at that time copies the appearance of the dynamic object as it is. However, there is an advantage in which, once a 3D model of the dynamic object is made, animation of a new motion or appearance edit and correction are easy.
Another technique group relates to methods of capturing appearance information and motion information of a dynamic object making a dynamic motion by using multi-viewpoint images of the dynamic object acquired from various viewpoints. In detail, there exist approaches according to whether an initial model is used, a model initialization method, an application range of multi-viewpoint image information, restoration priorities of an appearance and a motion, and a method of modifying the appearance of a model.
The trends of theses and dissertations are taking the approach of restoring appearance and motion information of a dynamic object by a method of modifying the appearance of the dynamic object by generating a unique body model of a dynamic object from a multi-viewpoint image of a 3D scanner or a main frame and applying the generated model of the dynamic object to each frame in order to minimize a projection error between multi-viewpoint silhouette information of each frame and multi-viewpoint silhouette information obtained by projecting the model of the dynamic object to each camera. However, it has been reported that, even though multi-viewpoint silhouette information is used, the information has a limit in expressing appearance information of a dynamic object making a dynamic motion, and in order to solve those problems, various correction methods based on user GUI has been suggested.
In a case of a 3D scanning method, there exists a limit in which unique modification features of the appearance, which do not appear when the initial model of the dynamic object, is not properly restored because of limitations in a local-shape modification method based on a mesh used to modify the appearance of the dynamic object.
In a case of a multi-viewpoint image technique, there is a drawback in which, since a modification of an appearance of a dynamic object according to the motion of each frame is restored by using appearance information of an initial model of the dynamic object, the multi-viewpoint image technique is highly dependent on the degree of precision of the appearance of the initial model of the dynamic object.